1. November / December 2014
in the spotlight 27
New Research
Fouls Bio-Fouling
ery recently, it was announced
that Mr J Antony Prince, a
Research & Development
scientist in Membrane Science and
Engineering from Environmental
and Water Technology Center of
Innovation (EWTCOI) at NgeeAnn
Polytechnic who is also doing PhD
in Newcastle University, UK, led a
team to develop a breakthrough in
bio-fouling.As Mr Prince described,
bio-fouling is the biggest drawback
and the most difficult type of fouling
to clean or regenerate the membrane
when using membrane technology
for water treatment. Water &
Wastewater Asia was privileged to
be able to speak to Mr Prince at
NgeeAnn Polytechnic in Singapore
to better understand this research
breakthrough, as well as its future.
One of the most pervasive
problems afflicting mankind
throughout the world is poor access
to clean freshwater and sanitation.
United Nations’ FAO states that by
2025, around 1.8 billion people will
be living in countries or regions
with absolute water scarcity, and
UNICEF has estimated that 2,000
children under the age of five die
every day from diarrhoeal diseases.
Of these, some 1,800 deaths are
linked to water, sanitation and
hygiene.
With the growing demand for
high quality water, many new
technologiesofwaterpurificationare
being developed to cater for potable
and non-potable use. The reliability
and ease of operation of membrane-
based filtration systems have led to
their proliferation in wastewater
treatment. Ultrafiltration (UF) is one
such well-developed low pressure
membrane separation process used
in different applications, such as
water & wastewater treatment,
reverse osmosis pretreatment and
separations in the food, dairy, paper,
textile, pharmaceuticals, chemical
and biochemical industries.
However, membrane fouling
remains an inevitable problem
in all pressure-driven membrane
processes causing deterioration of
the membrane performance and
membrane breakage, which lead
to high operational costs and short
replacement intervals and increase
the chemical usage. In fact, while
there are several cleaning methods
– such as physical (backwash)
and chemical (chemical cleaning)
methods – available to regenerate
the membrane, they require high
energy consumption and more
chemical usage.
Thisissueiswhatmotivated
Mr Prince to embark on
his research journey for a
solution to combat bio-
fouling. He believes
that while membrane
technology has been
well established in
the last half century,
present methods to
combat bio-fouling
not only require high
energy consumption
and chemical usage,
they are also
ineffective:

2. November / December 2014
in the spotlight28
“Current state of the art methods to overcome
bio-fouling are to modify the membranes with either
hydrophilic additives or with an antibacterial compound
(most commonly silver). It has been proven that silver
can kill the bacteria by rupturing the plasma membrane.
However, once the plasma membrane ruptures, the
negatively charged protoplasm compounds deposits onto
the positive surface of the membrane by electrostatic
attraction which will inactivate the silver ion/particle
eventually.”
Mr Prince strongly believes that prevention is always
better than cure, and with this in mind, he led his team to
develop an ultrafiltration membrane with a self-cleaning
surface which can prevent the fouling on the surface.
“If this is commercialised,” commented Mr Prince,
“the novel concept can help to reduce chemical
usage and operating costs significantly.”
How It Came to Be
Every research comes with a form of support, and for
Mr Prince, this was a collaboration between Ngee Ann
Polytechnic, Environmental and Water Technology
Centre of Innovation (EWTCOI)) and Newcastle
University International Singapore (NUIS), and funded
by the Singapore Ministry of Education (MOE) under
the Translational & Innovation Fund in 2013. The
research was the result of positive preliminary studies
while Mr Prince received the NU-Poly-SIT scholarship
from Newcastle University for his PhD in 2012, and this
partnership allowed Mr Prince to access NUIS’expertise
on new material development, as well as a local water
treatment company to apply this technology.
Figure 1: Schematic representation
of the self-cleaning property of the
membrane.
Source: Prince, J.A. et al. Self-cleaning Metal
Organic Framework (MOF) based ultrafiltration
membranes - A solution to bio-fouling in
membrane separation processes.
Sci. Rep. 4, 6555; DOI:10.1038/srep06555 (2014)

3. November / December 2014
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The Study
In this study, Mr Prince and his team proposed and
practised a novel concept to prevent bio-fouling by
developing a killing and self-cleaning membrane
surface having additional enhanced hydrophilicity with
highly negatively charged – NH2, - C00H and – OH
functional groups in addition to covalently attached
silver nanoparticles on the membrane surface Mr Prince
explained his thesis as follows:
“These functional groups have been shown to be
effective in combating the deposition of the negatively
charged colloidal particles, proteins, lipids, amino
acids and et cetera via an electrostatic repulsion and
hydrophobic-hydrophilic repulsion mechanisms.
“The anti-bio-fouling mechanism of the novel
membrane is illustrated in Figure 1. From the figure,
it can be easily understood that, when the bacteria
approaches the membrane surface, the antimicrobial
silver will kill them by rupturing their negatively charged
plasma wall (which leads to the leakage of negatively
charged protein molecules through the ruptured bacterial
cell wall), whereas the highly hydrophilic, negatively
charged acid, hydroxyl and amine functionalities will
prevent the deposition of these protein molecules
onto the membrane surface by electrostatic repulsion.
Thereby, the membrane can exhibit the self-cleaning
property. In addition to it, since theAgNPs are embedded
(covalently attached) in PEI matrix, the leaching of
AgNPs is completely prevented.”
The Problem
According to Mr Prince, the team has been working
in the field of water treatment for the last five years,
and encountered various types of fouling issues in low
pressure (UF & MF) membranes. Thus, they wanted to
focus on the development of a robust membrane material
that could combat this fouling issue by increasing the
membrane hydrophilicity. Mr Prince explained this
further:
“The current state-of-art technology in membrane
modificationsblendssilvernanoparticlesandhydrophilic
water soluble pore forming agents with polymeric dope
solution. Elution of these additives is unavoidable due
to the harsh operating condition. In this project, we have
carefully chosen the functional groups and the silver
nanoparticle which are chemically (covalently) attached
to them in order to overcome the elution of hydrophilic
additives and the leaching of nanoparticles.
“In the initial stages, we tried different methods of
increasing the hydrophilicity by blending hydrophilic
copolymers which eventually leached out during harsh
operations, and blending of sparingly soluble hydrophilic
additives resulted in the swelling of membranes. When
we tried to blend silver and other metal oxide nano
particle as a way to alleviate this fouling, it resulted in
leaching of these nano materials in the treated water.
Hence, we designed this unique polymer with covalently
attached hydrophilic functional groups and silver nano
particles to overcome this swelling and leaching issues
and to impart a permanent anti-fouling property.
“With this invention, we plan to develop unique
membrane materials with highly hydrophilic
functionality and antibacterial properties to reduce
membrane fouling in future.”
Future Directions
Mr Prince told WWA that, in addition to developing a
unique membrane material with Newscastle University,
the team intends to work closely with a local industrial
partner to test the technology in a realistic environment.
The team will also co-develop a pilot plant with the
company for further commercialisation purposes.
When prompted further about their plans, he added
that the technology is still in a premature stage for
commercialisation, and that at this point in time, the
company is not too much involved in the research.
Other Research Areas
While this research comes in very handy for businesses
that are demanding better water services, Mr Prince
has identified material development in membrane
technology where improvements could be made:
“Existing technologies have their own drawbacks,
and there is always room for improvements.
“For instance, in our recent research called
GLASSwater, we have developed a low cost ceramic
membrane by using used glass, which can reduce costs
by two to three times compared to commercial ceramic
membranes [1].This research was conducted in line with
expectations that new generation membrane materials
will improve the performance of the membranes due to
the recent popularity of ceramic membrane applications.
However, its high costs limit its usage in wastewater
treatment and hence, our development of low-cost
ceramic membranes could help water industry for
specific application like industrial waste water pre-
treatment.”
In addition to membrane technology, Mr Prince
highlighted that desalination systems are a viable
research area as well:
“Water is needed by every living object on the earth.
Fresh water shortage around the world is increasing at a
rapid rate due to the human population growth and the
scarcity of fresh water resources. The earth is covered by

4. November / December 2014
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Antony with his
PhD supervisor
almost 71% water by volume, 97% of which is seawater
and is inconsumable. The remaining 3% of the earth
water sources is considered fresh water. However, 98.8%
of the 3% is found in polar caps and underground. Only
about 0.03% of the world’s total water can be accessed
by humans, making fresh water a scarce resource. Since
such a high percentage of earth is filled with seawater,
converting seawater into potable water will solve many
of the water shortage problems. To be able to drink the
seawater, desalination is required.
“The current popular method of desalination is
reverse osmosis. Reverse osmosis is also based on
membrane technology and works by pressure difference
across the membrane. However, reverse osmosis
involves high energy and operating pressures, causing
it to have high operating costs. Other desalination
processes include multi-stage flash (MSF), multiple
effect evaporation (MEE), and thermal or mechanical
vapour compression (VC). However, on a large scale
basis, those thermal processes are too costly and
energy inefficient due to high energy consumption
rates. Hence, despite all the available desalination
processes, an alternative desalination offering lower
energy consumption is desired. Forward osmosis (FO)
and membrane distillation (MD) are two emerging low-
cost desalination technologies. These technologies are
in the developmental stage and many research groups
are focusing on these technologies.
Recently, we have developed a low cost desalination
system based on membrane distillation called Distil™.
The Distil™ system can reduce the desalination energy
by 40-50% compared to the conventional desalination
technologies [2] [3].”
Mr Prince also believes that, in order to accelerate
the uptake of new technologies in the municipal
and industrial sectors, it is important to close the gap
between fundamental research and commercialisation.
WWA
About the Study
The study was led by J Antony Prince who received the NU-Poly-SIT scholarship from Newcastle University for his PhD in 2012
under the guidance of Dr Kamelia Boodhoo (Senior lecturer Newcastle University), Dr S Bhuvana (R&D Scientist) and
Dr Gurdev Singh (Deputy Director) from EWTCOI with the support of two other researchers Ms V Anbharasi and Mr N Ayyanar
from EWTCOI.

5. November / December 2014
in the spotlight 31
Newcastle University International Singapore (NUIS) is
an established provider of top quality research in Singapore.
Building on its excellent research reputation in the UK, we are
engaging industry partners and high quality research degree
candidates in Singapore and South East Asia. NUIS’ areas of
expertise are broad and cover Food & Human Nutrition, Chemical
Engineering and Advanced Materials, Marine Engineering, Naval
Architecture, Offshore Engineering, Mechanical and System
Design, Electrical and Power Engineering, Civil Engineering
and Computing.
As a research-intensive institution, fostering links with
industry and local tertiary institutions are important to NUIS.
Through research partnerships, we aim to develop long- and
short-term research collaborations which are of mutual interest,
establish strategic collaboration focus and submit joint research
proposals for research funding. Our industry partners include
Danone, SembCorp, Singapore Technologies Electronics Ltd,
Large Scale Systems Group (LSG), International Paint Limited,
and Soil Machine Dynamics (SMD).
NUIS has a well-funded and growing research program
with over SGD7 million of projects currently being worked on.
Research funding comes from a mix of local and international
companies, government and independent agencies and through
collaborations with local tertiary institutes.
NUIS’ aim is to develop partnerships with international
academic establishments to provide teaching and research
opportunities. Newcastle University strives for world-class
academic excellence. NUIS’ business is to invest in people, build
capacities, export knowledge, develop skills, unleash intellect,
create future leaders and materialise dreams.
Newcastle University in the UK has been a destination of
choice for Singaporean students for decades. Newcastle’s
close relationship with many Singaporean industries together
with the excellent performance of graduates has meant that our
academic alliance with the Singapore Institute of Technology is
an outstanding success. Newcastle’s excellent reputation in many
subject areas will equip Singapore with cutting edge science and
technology, pioneering knowledge and techniques to address
global challenges for generations to come.
About Newcastle University International Singapore
References
1. http://www.eco-business.com/news/researchers-use-recycled-glass-to-filter-raw-water/
2. http://www.dutchcham.sg/novel-membrane-distillation-technology-for-desalination-unveiled
3. http://www.innovfest.sg/2013/pitch/NTP-E04-NP.pdf
Team photo